Technical Field
The present invention relates to an oxygen detecting multilayer body having an oxygen detecting function. More particularly, it relates to an oxygen detecting multilayer body, which can easily detect a color change of an oxygen detecting layer, and prevent an oxygen detecting layer from crazing. The invention further relates to an oxygen detecting packaging material using the oxygen detecting multilayer body and an oxygen absorber package packaged by the oxygen detecting packaging material.
Background Art
With respect to various articles which are susceptible to oxygen induced alteration or deterioration, such as a food, a beverage, a drug, a medical article, a cosmetic, a metal product, and an electronic product, an oxygen absorber is used for removing oxygen in a hermetic container keeping such an article, for purpose of storing the same for a long period while preventing oxidation deterioration.
Among various kinds of oxygen absorbers, there is an oxygen absorber with an oxygen detecting agent. An oxygen absorber with an oxygen detecting agent is an oxygen absorber in a sachet form or a sheet form, to which an oxygen detecting agent is attached, and when the inside of a hermetic container becomes in a deoxidized state, such an oxygen concentration in the hermetic container can be visually recognized through a color change of the oxygen detecting agent.
Heretofore, as an oxygen detecting agent an oxidation-reduction dye such as methylene blue has been used. However, an oxidation-reduction dye such as methylene blue is easily deteriorated by light irradiation. Therefore, it has been proposed to place an anchor coat layer or an overcoat layer imparted with a light screening property adjacent to an oxygen indicator layer using an oxidation-reduction dye (refer to Patent Literature 1). Further, since the dyeing power of methylene blue is so strong, that the same tends to migrate to the content, when the two are in contact tightly. Consequently, it has been proposed to place a transparent resin layer not allowing permeation of methylene blue, on an oxygen detecting layer (refer to Patent Literature 2).